The present invention relates to production method of 2,6- dichlorophenol compounds.
It is described that a kind of 2,6-dichlorophenol compounds are useful for intermediates to prepare dihalopropene compounds having insecticidal/acaricidal activity in U.S. Pat. No. 5,872,137 and U.S. Pat. No. 5,922,880. According to the descriptions, said 2,6-dichlorophenol compounds can be given by making a phenol compound react with t-butyl hypochlorite. (cf. col.4, 80 and 126 in U.S. Pat. No. 5,872,137 and col. 83-84, 90 and 106 in U.S. Pat. No. 5,922,880).
However, this preparation method does not give high yield, and so it is not sufficient to prepare the objected 2,6-dichlorophenol compounds.
On the other hand, the 2,6-dichlorination of 4-alkylphenol with chlorine gas is described in JP-sho55-40613A and JP-sho52-27734A. Further, the chlorination of methoxyphenol is described in Chemosphere vol. 17,pp. 1821-1829 (1988) and Ann. Rept. Takeda Res. Lab. vol. 26,pp. 138-148 (1967).
The object of the present invention is to provide a production method of the 2,6-dichlorophenol compounds useful for intermediates to prepare the dihalopropene compounds having insecticidal/acaricidal activity.
The present invention provides a method for producing the 2,6-dichlorophenol compounds given by formula (1): 
wherein R represents a 3,3-dihalo-2-propenyl group or a benzyl group optionally substituted by halogen atom(s), which comprises making a phenol compound given by formula (2): 
wherein R has the same meaning mentioned above, react with sulfuryl chloride in the presence of a secondary amine, and the method gives high yield of the product.
In the present invention, the 3,3-dihalo-2-propenyl group for R is exemplified by 3,3-dichloro-2-propenyl group and 3,3-dibromo-2-propenyl group. Further, the benzyl group optionally substituted by halogen atom(s) is exemplified by a benzyl group whose hydrogen atom(s) on its benzene ring may be substituted by at least one halogen atom, and the typical examples are benzyl group and 4-chlorobenzyl group.
The present production method is characterized by the reaction of the phenol compound given by formula (2) with sulfuryl chloride in the presence of a secondary amine.
The reaction is usually carried out in a solvent. Examples of the solvent used for the reaction include aromatic hydrocarbons such as benzene, toluene, xylene, mesitylene, ethylbenzene and so on; aliphatic hydrocarbons such as hexane, heptane, octane and so on; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, benzotrifluoride and so on; and mixtures thereof.
Examples of the secondary amine used for the reaction include dialkylamine such as di(C2-C6)alkylamine; dialkenylamines such as di(C3-C6)alkenylamine; alkylalkenylamines such as (C2-C6)alkyl(C3-C6) alkenylamine; and dicycloalkylamines such as di(C3-C6)cycloalkylamine. Typical dialkylamines are diethylamine, dipropylamine, dibutylamine, dipentylamine, dihexylamine, diisopropylamine, di-sec-butylamine, ethylpropylamine and so on. Typical dialkenylamines are allylpropylamine, di(3-butenyl)amine and so on. Typical alkylalkenylamines are allylpropylamine and so on. Typical dicycloalkylamines are dicyclopropylamine, dicyclobutylamine, dicyclopentylamine, dicyclohexylalamine and so on
The amount of the secondary amine used for the reaction is usually 0.001 to 1 mol based on 1 mol of the phenol compound given by formula (2), preferably 0.001 to 0.1 mol in the view of good operation for treatment after the reaction.
The amount of the sulfuryl chloride used for the reaction is usually 1.5 to 3.0 mols, preferably 2.0 to 2.5 mols based on 1 mol of the phenol compound given by formula (2) in the view of good yield.
The reaction temperature is usually in the range of 0 to 100xc2x0 C., and the reaction period is usually in the range of 1 to 24 hours.
The reaction can be, for example, carried out by the followings.
1) A method of dissolving the phenol compound given by formula (2), the secondary amine and sulfuryl chloride in a solvent and stirring them.
2) A method of dissolving the phenol compound given by formula (2) and the secondary amine in a solvent and adding sulfuryl chloride dropwise to the solution under stirring.
3) A method of dissolving the secondary amine in a solvent, and adding the phenol compound given by formula (2) and sulfuryl chloride dropwise to the solution under stirring.
The status of the reaction can be confirmed by analyzing the reaction mixture by analyzing means such as high performance liquid chromatography, gas chromatography, thin layer chromatography and so on.
After the reaction, the work-up procedures, for example, mentioned below can make the 2,6-dichlorophenol compound given by formula (1) isolated.
1) Pouring the reaction mixture into acidic water (e.g. hydrochloric acid, aqueous sulfuric acid), separating the organic solvent from water and concentrating the obtained organic layer.
2) Pouring the reaction mixture into week basic water (e.g. aqueous sodium hydrogencarbonate), separating the organic solvent from water and concentrating the obtained organic layer.
3) Adding an aqueous solution of a reducing agent (e.g. sodium sulfite, sodium hydrogensulfite, sodium thiosulfate) to the reaction mixture, stirring for 0.1 to 24 hours at 0 to 100xc2x0 C., separating the organic solvent from water and concentrating the obtained organic layer.
The isolated 2,6-dichlorophenol compound given by formula (1) can be further purified by column chromatography, recrystallization and so on.